1. Field of the Invention
The present invention relates to monitoring apparatuses for preventing unauthorized use of image forming apparatuses such as copying machines and multifunctional peripherals by users.
2. Description of the Related Art
There are image forming apparatuses capable of performing various jobs such as copying, network printing, facsimile communication, and e-mail transmission. Some of the image forming apparatuses have a function of storing various event logs such as registered user authentication logs, operation logs, and job logs. The logs are collectively referred to sometimes as “audit log.” An audit log is recorded together with user identification information (hereinafter, “user ID”) on the user having ordered an event. The audit log specifies records of user operations and works as a psychological deterrent to unauthorized use by users to discourage the users from committing such use.
To prevent unauthorized use, capturing images by a monitoring camera is also effective. Some monitoring cameras sequentially store video data representing captured video images on a recording server communicably connected via a network. Japanese Patent Application Laid-Open No. 2008-197152 discusses a technique using a combination of an image forming apparatus and a monitoring camera to prevent unauthorized use. According to the technique discussed in Japanese Patent Application Laid-Open No. 2008-197152, video data representing a video image of the user that is captured by the monitoring camera from the start to the end of a job is associated with the job and managed by the image forming apparatus.
Image forming apparatuses used in offices are generally set to allow guest users to use the image forming apparatuses. Allowing a user not registered in an image forming apparatus to use the apparatus as a guest user enables, for example, a guest or a user of another department to use limited functions. The monitoring log is stored only for the users that logged in. Thus, in a case where a user uses the image forming apparatus as a guest user, it is not possible to identify the user from the audit log.
Further, according to Japanese Patent Application Laid-Open No. 2008-197152, users including guest users can be identified from the video images for each job. However, since the video images are managed for every job, the amount of video data increases. Thus, it takes time to extract a target video image and identify the user having executed the job.